dyke swarms emplacement constitutes one of the conspicuous features of the neoproterozoic arabian-nubian shield (ans) (~950-540ma). based on field investigations, petrographic and geochemical characteristics the dyke swarms in nw sinai (egypt) comprise of mafic (dolerite-trachy-basalt-basalt), intermediate (basaltic-andesite trachy-andesite) and felsic (rhyodacite-rhyolite) varieties. geochemic...

, 65, 85–87.Prasad, N. and Roscoe, S.M., 1996. Evi-dence for anoxic to oxic atmosphericchange during 2.45–2.22 Ga from lowerand upper sub-Huronian paleosols.Catena, 27, 105–121.Prave, A.R., 1999a. Two diamictites, twocap carbonates, two dC excursions,two rifts: the Neoproterozoic KingstonPeak Formation, Death Valley, Califor-nia. Geology, 27, 339–342....

Because animals require oxygen, an increase in late-Neoproterozoic oxygen concentrations has been suggested as a stimulus for their evolution. The iron content of deep-sea sediments shows that the deep ocean was anoxic and ferruginous before and during the Gaskiers glaciation 580 million years ago and that it became oxic afterward. The first known members of the Ediacara biota arose shortly aft...

Isotope stratigraphy of the Lapa Formation, São Francisco Basin, Brazil: Implications for Late Neoproterozoic glacial events in South America Karem Azmy a,∗, Alan J. Kaufman b, Aroldo Misi c, Tolentino Flávio de Oliveira d a Department of Earth Sciences, Memorial University of Newfoundland, St. John’s, Nfld A1B 3X5, Canada b Geology Department, University of Maryland, College Park, MD 20742, US...

The increase in trace fossil diversity across the Neoproterozoic-Cambrian boundary often is presented in terms of tabulations of ichnogenera. However, a clearer picture of the increase in diversity and complexity can be reached by combining trace fossils into broad groups defined both on morphology and interpretation. This also focuses attention on looking for similarites between Neoproterozoic...

13 Ž . New records of the abundance of C in marine organic matter have been compiled for i the later Neoproterozoic, from Ž . Ž . Ž . Ž . 800 to 543 Ma 346 analyses , ii the Cambrian through the Jurassic 1616 analyses , and iii the Cretaceous and Cenozoic Ž . 13 2493 analyses . Comparison of these to existing compilations of the abundance of C in sedimentary carbonates has Ž . allowed developme...